B2 Cell division

Question 1

What do each of your cells have?

Answer 1

a nucleus that contains chromosomes

Question 2

What do chromosomes carry?

Answer 2

the genes that contain the instructions for making both new cells and all the tissues and organs needed to make an entire new you

Question 3

What is a gene?

Answer 3

a small packet of information that controls a characteristic,or part of a characteristic, of your body. It is a section of DNA, the unique molecule that makes up your chromosomes

Question 4

What are your characteristics a result of? one or many genes?

Answer 4

many

Question 5

Genes are grouped together on …………..

Answer 5

chromosomes

Question 6

How many chromosomes are there in the nucleus of your body cells?

Answer 6

46

Question 7

What are the 46 chromosomes arranged into?

Answer 7

23 pairs

Question 8

In each pair of chromosomes, one chromosome is inherited from the …….. and one from the ……….

Answer 8

father
mother

Question 9

What are sex cells called?

Answer 9

gametes

Question 10

What is a karyotype

Answer 10

an individual’s complete set of chromosomes

Question 11

what is the cell cycle?

Answer 11

body cells dividing in a series of stages

Question 12

What type of cell division is in the cell cycle?

Answer 12

mitosis

Question 13

What type of cells does mitosis create?

Answer 13

two identical daughter cells

Question 14

What does cell division by mitosis create?

Answer 14

additional cells needed for growth, development and repair

Question 15

What is the length of the cell cycle?

Answer 15

less than 24 hours to several years

Question 16

When is the cell cycle shortest?

Answer 16

when it is a baby

Question 17

When is the cell cycle slowest?

Answer 17

as a fully grown adult

Question 18

Describe the stages of the cell cycle

Answer 18

stage 1 - this is the longest stage in the cell cycle. The cell grow bigger, increase their mass, and carry out the normal cell activities. Most importantly they replicate their DNA to form two copies of each chromosome ready for cell division, They also increase the number of sub-cellular structures such as mitochondria, ribosomes and chloroplasts ready for the cell to divide
stage 2 - mitosis: in this process one set of chromosomes is pulled to each end of the dividing cell and nucleus divides
stage 3 - this is the stage during which the cytoplasm and the cell membranes also divide to form two identical daughter cells.

Question 19

Describe the 3 stages of mitosis

Answer 19

stage 1 - this normal body cell has four chromosomes in two pairs
stage 2 - in the first stage of the cell cycle, a copy of each chromosome is made
stage 3 - the cell divides in two to form two daughter cells, each with a nucleus containing four chromosomes identical to the ones in the original parent cell

Question 20

Why are the cells of your body not the same as the original cell?

Answer 20

Cells divide, grow and develop and also differentiate

Question 21

What is differentiation?

Answer 21

the process by which cells become specialized to perform specific functions in an organism

Question 22

In early development of animal and plant embryos, the cells are ………. . these are called ………. and can become an type of cell that is needed

Answer 22

unspecialised
stem cells

Question 23

When are most of a humans cell specialised?

Answer 23

by the time a baby is born

Question 24

What replaces dead or damaged cells?

Answer 24

multipotent adult stem cells

Question 25

What are cell division used for in mature animals?

Answer 25

repair and replacement
(not growth)

Question 26

undifferntiated cells are formed at ………. regions of the ……. and …….., known as ………..

Answer 26

active
shoots
roots
meristems

Question 27

What can meristems cells be called?

Answer 27

shoot tips or root tips

Question 28

What happens in a plants active region?

Answer 28

mitosis is taking place almost constantly

Question 29

Plants keep growing all through their lives at these ……………

Answer 29

growing points

Question 30

What happens to the plant cells produced when the plant is growing?

Answer 30

they don’t differentiate until they are in their final position in the plant and even then the differentiation isn’t permanent and it can move and re-differentiate unlike animal cells

Question 31

Producing identical offspring is known as what?

Answer 31

cloning

Question 32

Why can a lead tissue produce huge numbers of identical plant

Answer 32

because in the right condition a plant cell will become unspecialised and undergo mitosis many times. each of these undifferentiated cells will produce more cells by mitosis

Question 33

How do you get the specialised plant cells?

Answer 33

By altering the conditions they will form different cells needed to form a tiny new plant

Question 34

Why is it difficult to clone animals?

Answer 34

Because most animal cells differentiate permanently early in embryo development and cant turn back. so artificial animal clones can only be made by cloning embryos in some way, adult cells can be used to make an embryo

Question 35

What is a zygote

Answer 35

A single cell formed by an egg and sperm cell fusing

Question 36

What can a zygote divide into?

Answer 36

an embryo - a hollow ball of cells

Question 37

What are the inner cells in the zygote formed nucleus?

Answer 37

embryonic cells

Question 38

embryonic stem cells are ………..

Answer 38

pluripotent

Question 39

What happened in 1998 due to a breakthrough in the stem cell industry

Answer 39

Two scientists managed to culture human embryonic stem cells, capable of forming other types of cell

Question 40

Why does the 1998 breakthrough in the stem cell industry help people with issues due to parts of their body stopping working properly?

Answer 40

embryonic stem cells can be encouraged to grow into almost any different type of cell needed in the body

Question 41

What can treatment with stem cells be able to help?

Answer 41

(paralysis, diabetes), tissue rejection,

Question 42

What technique is used to get around the issue of tissue rejection?

Answer 42

therapeutic cloning

Question 43

What is therapeutic cloning?

Answer 43

creating stem cells using the patients DNA

Question 44

What are the 6 stages of therapeutic cloning?

Answer 44

1. obtain a donor egg cell
2. Obtain a body cell (cheek cell) from the patient
3. Remove the nucleus from the donor cell and place the nucleus from the cheek cell into the donor egg cell
4. Stimulate cell division by mitosis by giving the egg cell an electric shock
5. Leave the cell to divide for 4-5 days
6. The resulting embryo has stem cells removed for use in the patient

Question 45

What are concerns for using stem cells in humans?

Answer 45

-embryo is destroyed
-shortage of egg donors
-risk of egg donation
-Viral infection
-side effects might be harmful, sometimes it can cause cancer
-poor success rate, it is difficult to get eggs and difficult to create the embryo

Question 46

What are positives for using stem cells in humans

Answer 46

-cure disease
-producing replacement cells that are healthy
-Embryonic stem cells can differentiate into any type of cell (pluripotent)
-Reduce the waiting list for organ transplants
-Scientists can use the stem cell research (maybe to find effective drugs)

Question 47

How is a sperm cell specialised

Answer 47

carrying the male genetic material to the egg for reproduction

Question 48

How is a nerve cell specialised

Answer 48

Carrying electrical impulses around the body

Question 49

How is a muscle cell specialised

Answer 49

Contracting an relaxing to allow movement

Question 50

How is a liver cell specialised?

Answer 50

Breaking down poisons in the blood and making bile

Question 51

How is a red blood cell specialised?

Answer 51

Transporting oxygen around the body from lungs to tissues